A Comprehensive Examination of Bipolar Coil with and without Ferrite Couplers

Wireless charging has gained significant popularity due to its convenience in charging electronic devices without cables. However, aligning the receiver coil with the charging pad’s center is crucial for effective charging, which reduces the user convenience of wireless charging. This paper addresses this limitation and aims to improve the coupling of device placement by designing a dual D-coil (Bipolar) structure. It is observed that using a ferrite coupler and aluminum shielding improves the magnetic parameter as compared to the coupler and shielding. However, when the coils are misaligned, the efficiency improves, resulting in enhanced freedom of device placement. A dualcoil structure is proposed to improve power transfer efficiency compared to a single polarity coil. Simulation and measurement results confirm that the proposed coil design enhances the freedom of device placement while improving efficiency.